Shu-Zheng Liu et al. - Abstracts of Research at MH Radiobiology Laboroatory

RSH > Documents > Liu et al., 85 Abstracts, 1995-1999. (See also 113 ABSTRACTS-2000-2007 Word doc [47 pages, 340KB]).

1. Liu Shuzheng, Zhang Yingchun, Su Xu. Effect of low dose radiation on the expression of TCR/CD₃and CD₂₅ molecules in the plasma membrane of mouse thymocytes. Chin. J. Pathophys., 1995, 11(1):2-5.	Abstract: It is reported for the first time in the present paper that whole-body irradiation (WBI) with low dose X-rays could facilitate the expression of TCR (T-cell receptor), CD₃ and CD₂₅ molecules on the surface of mouse thymocytes. It has been previously reported from this laboratory that low dose radiation could potentiate the thymocyte renewal. In order to study the effect of low dose radiation on the process of maturation and differentiation of thymocytes, flow cytometry with immunofluorescence was used to examine the changes in expression of TCR/CD₃ and CD₂₅ molecules on the thymocytes after WBI with 75 mGy X-rays. It was found that 4-24 hours after irradiation the expression of TCR/CD₃ on the surface of thymocytes increased with time, suggesting an expedited maturation and differentiation of the thymocytes. The expression of CD₂₅ (interleukin 2 receptor alpha) of the Con A-stimulated thymocytes was markedly potentiated 24 h after irradiation, indicating an up-regulation of their functional activity. The significance of the increased expression of these molecules on thymocytes and its role in the facilitation of T-lymphocyte signal transduction after low dose radiation were discussed.	75 mGy X-rays WBI increased T-cell receptor and CD₃ expression on mouse thymocyte surfaces for 4-24 hours, indicating expedited thymocyte maturation and differentiation, and CD₂₅ (interleukin-2 receptor) expression of Con A-stimulated thymocytes was markedly potentiated 24 h after irradiation, indicating up-regulation of their functional activity. The significance of these effects is discussed.
2. Li Xiuyi, Fu Hanqing, Liu Shuzheng. Whole-body low dose irradiation enhances the tumor-suppressive effect of high dose local irradiation given to the tumor site. J. N. Bethune Univ. Med. Sci., 1995, 21(6):559-562.	Abstract C57BL/6 mice implanted subcutaneously with Lewis lung carcinoma cells were used as a model in the present report. When the tumor-bearing mice were give whole-body irradiation (WBI) with 75 mGy X-rays 24 h before a local irradiation with 10 Gy X-rays to the tumor site, the suppressive effect on tumor growth was found to be greater than that following local irradiation with 10 Gy alone. A Winn assay was performed with subcutaneous implantation into normal mice of a mixture of Lewis lung cancer cells and splenocytes from tumor-bearing mice with or without WBI with 75 mGy. It was observed that the tumor growth rate was lower in the animals implanted with a mixture of cancer cells with splenocytes from low dose irradiated tumor-bearing mice than in those implanted with a mixture of cancer cells with splenocytes from sham-irradiated tumor-bearing mice and the time of appearance of the tumor was found to be earlier in the latter group, the difference being more marked at an E:T ratio of 50:1. These results implicate that the increased tumor-suppressive effect might be due to a potentiation of immunological reactions after WBI with low dose X-rays.	Tumor growth rate was lower in mice implanted with a mixture of cancer cells with splenocytes from low dose-irradiated tumor-bearing mice, and the tumor appeared later, vs. sham-irradiated tumor-bearing mice. The tumor-suppressive effect may be due to a potentiation of immunological reactions after LDR.
3. Zhao Yong, Gong Shouliang, Liu Shuzheng. Time-effect relationship of immunological adaptive response induced by low dose X-irradiation in mice. J. N. Bethune Univ. Med. Sci., 1995, 21(5):441-443.	Abstract In the present study, Kunming mice irradiated with whole-boy X-rays were used to observe time-effect relationship of immunological adaptive response induced by ionizing radiation. The results showed that preirradiation dose of 75 mGy X-rays with the intervals of 6-48 h between pre-irradiation and challenge irradiation could induce immunological adaptive response in the spontaneous proliferation of thymocytes and the responses of splenocytes to Con A and LPS in mice at 18-24 h after challenge irradiation with 1.5-2.0 Gy X-rays.	Preirradiation of mice by 75 mGy X-rays at 6-48 h intervals before a challenge irradiation induced immunological adaptive response in the spontaneous proliferation of thymocytes, and in the responses of splenocytes to Con A and LPS at 18-24 h after 1.5-2.0 Gy X-rays challenge irradiation.
4. Su Xu, Zhang Yingchun, Liu Shuzheng. Radiation-induced apoptosis in thymocytes as determined by flow cytometry. J. Radiat. Res. Radiat. Proces., 1995, 13(2):126-128.	Abstract Programmed cell death (PCD), or apoptosis, is a conceptually different way of cell death from necrosis. PCD plays an important role in immunologic regulation. PCD in thymocytes was analyzed by flow cytometry following in vitro X-irradiation. It was found that culturing of thymocytes could induce PCD that showed a time dependent increase. Four hours after culturing, 16% of thymocytes was found in the Ao region (PCD is shown in the Ao region of the histogram of flow cytometry). PCD in thymocytes showed a time dependent increase after 2.0 Gy X-irradiation, being significantly higher than that in the control at the same culturing time. 24 hours after X-irradiation in vitro, it was found that with doses below 100 mGy PCD was not significantly different from the control at the same culturing time. But when the doses were above 100 mGy, PCD showed a dose dependent increase, being significantly higher than that of the control at the same culturing time. These results are important in the understanding of the biological effects of low dose radiation.	Culturing of thymocytes induced PCD (apoptosis), with a time-dependent increase, following X-ray, significantly higher than control. Below 100 mGy, PCD was not significantly different from control at the same culturing time; above 100 mGy, PCD had a dose-dependent increase, significantly higher than control. These results are important in understanding the biological effects of LDR.
5. Chen Zhiyun, Zhang Ming, Liu Shuzheng. Effects of low dose irradiation on the splenic macrophage function in mice. J. Radiat. Res. Radiat. Proces., 1995, 13(3):186-189,192.	Abstract It is known that low dose ionizing radiation stimulates the immune functions in human subjects and mice. In order to examine the situation of macrophages a series of changes in the immune system in Kunming mice following low dose whole body irradiation were observed based on the study of macrophages from spleen. The present study was designed by whole body X-rays with the doses of 50, 75, 100 and 250 mGy, respectively. The dose rate was 12.5 mGy/min. All the results showed that low dose irradiation may enhance the function of macrophages on the reaction of lymphocytes to Con A, and increase content of IL-1 from macrophages.	X-rays at 50, 75, 100, and 250 mGy WBI, at 12.5 mGy/min, enhanced macrophage function on the reaction of lymphocytes to Con A; and increased the content of IL-1 from macrophages.
6. Liu Shuzheng. Current status of research on radiation hormesis in the immune system after low level radiation. J. Radiat. Res. Radiat. Proces., 1995, 13(3):129-139. (in English)	Abstract The present paper highlights the chief results of experimental studies recently carried out in the author’s laboratory on the stimulatory effects of low level radiation on immunity. The intercellular relationship within the immune system after whole-body irradiation (WBI) with low doses of X- and gamma-rays was briefly outlined with the emphasis on the potentiating effect of low dose radiation (LDR) on the helper T cells, which was thought to occupy a pivotal position in the process of immuno-stimulation. Data suggesting the facilitation by LDR of the signal transduction process within the T cells were presented. Some hypotheses prevailing in the literature for the explanation of the stimulatory effect of LDR were critically evaluated. Existing experimental data both from the literature and from the author’s laboratory were analyzed giving no strong support to the speculation of either the preferential deletion of the radiosensitive suppressor T subset or the increased apoptosis of the T cell "precursors" in the thymus leading to secondary immunologic augmentation by low doses which stimulate immune functions. The possible influence of systemic changes, especially those in the neuroendocrine regulation, on the T cell potentiation following LDR was suggested. Finally the biological implications of the hormetic effects of LDR were discussed.	Results of LDR studies of stimulatory effects on immunity in the author’s laboratory: on the intercellular relationship within the immune system from X- and g-ray WBI on potentiating effect on helper-T-cells, thought to be significant in immuno-stimulation; and suggestions that LDR facilitates signal transduction within T-cells. No literature, nor the author’s experiments, strongly support speculation that either the preferential deletion of the radiosensitive suppressor-T subset, or the increased apoptosis of the T-cell "precursors" in the thymus, lead to secondary immunologic augmentation by LDR which stimulate immune functions. Possible systemic changes, especially in neuroendocrine regulation, on T-cell potentiation following LDR, and biological implications to LDR hormetic effects, are discussed.
7. Liu Shuzheng, Zhang Yingchun, Mu Ying, Liu Jianxiang. Radiation effect on thymocyte apoptosis. J. N. Bethune Univ. Med. Sci., 1995, 21(6):551-557. (in English)	Abstract Thymocyte apoptosis as assessed by counting apoptotic bodies with flow cytometry (FCM) and measuring DNA fragmentation with fluorescence spectrophotometry (FSP). J-shaped dose-response curves were obtained after both whole-body irradiation (WBI) of mice and in vitro irradiation of EL4 cells with doses ranging from 0.025 to 4 Gy X-rays, with a significant reduction of apoptosis rate to below normal level with doses within 0.2 Gy and a dose-dependent increase of apoptosis with doses above 0.5 Gy. WBI of mice with 75 mGy X-rays reduced thymocyte apoptosis 4 and 24 h after irradiation. When thymocytes were cultured 24 after WBI with 75 mGy X-rays in complete RPMI 1640 medium, a reduction of apoptosis was observed in the course of incubation for 72 h and the presence of Con A in the medium accentuated this reduction in a dose- and time-dependent manner. The possible mechanisms and implications of these observations are discussed and future studies are proposed.	Both WBI of mice, and in-vitro irradiation of EL4 cells, with 0.025 to 4 Gy X-rays, produced J-shaped dose-responses. The apoptosis rate was significantly reduced below 0.2 Gy, with a dose-dependent increase above 0.5 Gy. 75 mGy X-ray WBI reduced thymocyte apoptosis 4 and 24 h after irradiation in mice. Thymocytes cultured 24 after 75 mGy X-ray WBI, had reduced apoptosis during 72 h incubation; and Con A in the medium accentuated this reduction in a dose- and time-dependent manner. Possible mechanisms and implications are discussed.
8. Liu Weihong, Gong Shouliang, Liu Shuzheng. Immunological effect of low dose radiation and its mechanism. J. N. Bethune Univ. Med. Sci., 1995, 21(3):223-226. (in English)	Abstract A series of changes in the immune functions in mice were found after low dose radiation with either single X-rays or continuous g -rays. The plaque-forming cell (PFC) reaction in the spleen was stimulated. The ratio of Ts to Th didn’t change. Neither Ts activity in the spleen induced by Con A nor the short life-span Ts activity of splenocytes and thymocytes was inhibited. The T cell functions were activated. DNA, RNA and protein synthesis in response to Con A were significantly enhanced. The IL-2 production by the splenocytes also increased. Simultaneously, the contents of norepinephrine and epinephrine in the spleen increased and the concentrations of enkephalins in the hypothalamus markedly decreased. These results indicated that the changes of neuroendocrine regulative functions might be involved in the stimulatory effects of immune functions after low dose radiation.	Immune functions were changed in mice after LDR with either single X-rays or continuous g-rays: 1) The plaque-forming cell (PFC) reaction in the spleen was stimulated. 2) The ratio of T_s to T_h did not change; and neither the T_s activity in the spleen induced by Con A, nor the short life-span T_s activity of splenocytes and thymocytes, was inhibited. 3) The T-cell functions were activated. 4) DNA, RNA, and protein synthesis in response to Con A were significantly enhanced. 5) IL-2 production by the splenocytes increased. 6) Simultaneously, the contents of norepinephrine and epinephrine in the spleen increased; and enkephalins concentrations in the hypothalamus markedly decreased. Neuroendocrine regulative function changes might be involved in the stimulatory effects of immune functions after LDR.
9. Zhao Yong, Gong Shouliang, Liu Shuzheng. Effect of 5-HT on immune functions of mouse splenocytes irradiated with low doses. J. Radiat. Res. Radiat. Proces., 1995, 13, (3):173-176.	Abstract The present study was designed to observe the effects of 5-HT on the immune functions of the splenocytes irradiated with 75 mGy X-rays in Kunming male mice in vivo and in vitro. The results showed that 5-HT inhibited significantly the spontaneous proliferation of the normal splenocytes, but the effects of 5-HT on the responses of the normal splenocytes to Con A were not obvious. The response of the splenocytes to Con A after X-irradiation with 75 mGy both in vivo and in vitro was enhanced in certain concentrations of 5-HT. The results suggest that 5-HT in certain amount may inhibit the splenocyte immune functions and participate in the immunoenhancement effect following low dose irradiation. But the effects of certain 5-HT concentrations on the proliferation of the splenocytes irradiated in vivo and in vitro were different. It increased in vivo, but was inhibited in vitro. It is supposed that it may be related to the changes of the internal environment of the splenocytes.	In splenocytes irradiated with 75 mGy in vivo and in vitro, 5-HT inhibited spontaneous proliferation significantly, but Con A responses were not obviously effected. Splenocyte response to Con A was enhanced in certain 5-HT concentrations. 5-HT in certain amounts may inhibit splenocyte immune functions and participation in the immuno-enhancement effect following LDR. In certain 5-HT concentrations, splenocyte proliferation irradiated in vivo increased, but was inhibited in vitro. This may relate to splenocyte internal environment changes.
10. Su Xu, Zhang Yingchun, Liu Shuzheng. Influence of ionizing radiation on the cell cycle progression of thymocytes in mice. J. N. Bethune Univ. Med. Sci., 1996, 22(6):580-582.	Abstract The present study was designed to examine the cell cycle progression of mouse thymocytes and its dose-effect relationship following whole-body irradiation (WBI) using flow cytometry. It was found that after WBI with 4 Gy X-rays DNA synthesis was suppressed with significant G₂ block beginning from 4 hours and reaching its peak at 8 hours. Dose-effect study showed that DNA synthesis was stimulated with doses within 0.2 Gy, above which the opposite effect occurred together with G₂ block and cell division delay.	Cell cycle progression of mouse thymocytes following 4 Gy X-ray WBI found that, DNA synthesis was suppressed with significant G₂ block from 4 hours, with a peak at 8 hours. With doses within 0.2 Gy, DNA synthesis was stimulated, above which the opposite effect occurred, together with G₂ block and cell division delay.
11. Zhao Yong, Gong Shouliang, Liu Shuzheng. Effects of acetulcholine on proliferative reaction of murine splenocytes irradiated with low dose radiation. J. Radiat. Res. Radiat. Process., 1996, 14(4):231-234.	Abstract The present study was designed to observe the effects of acetylcholine (Ach) on the proliferative reaction of the splenocytes irradiated with low dose X-rays in Kunming male mice in vivo and in vitro. The results showed that Ach enhanced significantly the spontaneous proliferations of the splenocytes and the responses of the splenocytes to Con A. However, the immune functional change of the splenocytes irradiated with 75 mGy in vivo and in vitro was found to be different. It increased to a greater extent in vivo than in vitro. These results suggest that Ach may stimulate the splenocyte proliferative reaction and participate in the immunoenhancemewnt following low dose radiation to a certain extent. However, the action mechanism of Ach on the immune functional changes of the splenocytes irradiated with low dose X-rays in vivo and in vitro may be different. It is supposed to be related to the change of the microenvironment of the splenocytes.	X-ray LDR of splenocytes in mice in vivo and in vitro showed that Acetylcholine (Ach) significantly enhanced spontaneous proliferation, and responses to Con A. However, when irradiated with 75 mGy, splenocyte immune functional changes increased more in vivo than in vitro. Ach may stimulate the splenocyte proliferative reaction and participate in the immuno-enhancement following LDR to a certain extent. However, Ach effects mechanisms on splenocyte immune functional changes with LDR in vivo and in vitro may be different, and may be related to changes in the splenocytes' microenvironment.
12. Gong Shouliang, Zhao Yong, Liu Shuzheng. Role of changes of functional status of hypothalamo-pituitary-gonadal axis in immunoenhancement following low dose radiation. Chin. J. Pathophys., 1996, 12(3):231-234.	Abstract The whole body of Kunming male mice was irradiated with dose of 75 mGy X-rays. The results showed that hypothalamic 5-HT contents increased and serum LH, FSH and testosterone (TS) levels decreased, accompanied with lowering of TS receptors in the cytoplasm and the cell nucleus of the splenocytes. After intrahypothalamic injection of 5-HT the changes of serum LH and FSH levels in Wistar male rats were consistent with the changes of these hormones in the mice after 75 mGy irradiation. The above-mentioned results suggested that low dose radiation might activate the central 5-HT neurons, leading to the increase of hypothalamic 5-HT production and secretion and the functional down regulation of gonadal axis, and partially relieve the normally existing inhibition of hypothalamo-pituitary-gonadal system on immune organs, thus inducimg the enhancement of immune function.	Mice irradiated with 75 mGy X-rays increased hypothalamic 5-HT contents and serum LH, and decreased FSH and testosterone (TS) levels, with lowering of TS receptors in the splenocyte cytoplasm and cell nucleus. In rats, after 5-HT intrahypothalamic injection, serum LH and FSH levels changes were consistent with these hormone changes in the mice after 75 mGy irradiation. LDR might activate the central 5-HT neurons, increasing hypothalamic 5-HT production and secretion, and the functional down-regulation of gonadal axis, and partially relieve the normally existing inhibition of the hypothalamo-pituitary-gonadal system on immune organs, thus inducing enhanced immune function.
13. Wan Hong, Liu Shuzheng. Enhanced expression of c-fos protooncogen in mouse lymphoid organs following low dose radiation. J. Radiat. Res. Radiat. Proces., 1996, 14(4):244-247.	Abstract In situ hybridization was used to examine the expression of c-fos mRNA in mouse thymus, spleen and lymph node following whole body irradiation (WBI) with 75 mGy X-rays. The results showed that the basal expression of c-fos mRNA in macrophages, interdigitating cells and some large lymphocytes of thymus, spleen and mesenteric lymph node was markedly enhanced after WBI with 75 mGy X-rays. The expression of c-fos mRNA in the thymus and spleen reached its peak 1 h and 2 h after irradiation respectively and both returned to the sham-irradiated level 12 h after irradiation. However, the increase in expression of c-fos mRNA in the lymph node was not so marked but lingered longer after irradiation. The implications of these findings were briefly discussed in connection with our previous data.	Following 75 mGy X-rays, c-fos mRNA expression was markedly enhanced in macrophages, interdigitating cells, and some large lymphocytes of the thymus, spleen, and mesenteric lymph node. It peaked in the thymus and spleen at 1 h and 2 h after irradiation respectively. Both returned to sham-irradiated levels 12 h after irradiation. Increases in lymph nodes were not so marked, but lingered longer after irradiation. These findings are discussed, connected to our previous data.
14. Wan Hong, Gong Shouliang, Liu Shuzheng. Expression of c-fos protooncogene in mouse brain following low dose irradiation. Chin. J. Radiol. Med. Prot., 1996, 16(1):15-17.	Abstract In situ hybridization was used to examine the expression of c-fos mRNA in the mouse brain following whole body irradiation (WBI) with 75 mGy X-rays. The results showed that WBI with 75 mGy could stimulate the expression of c-fos in extensive areas of neurons in the mouse brain, especially in the cerebral cortex and hypothalamus. The c-fos mRNA appeared 15 min after irradiation, reached its peak within 1 h and began to fade at 2 h with its total disappearance 8 h after irradiation. These findings indicate that low dose radiation can enhance the activity of the neurons in certain areas of the brain.	Following 75 mGy X-rays, c-fos mRNA expression was stimulated in extensive areas of neurons in the mouse brain, especially in the cerebral cortex and hypothalamus. The c-fos mRNA appeared 15 min after irradiation, reached its peak within 1 h, and began to fade at 2 h, disappearing 8 h after irradiation. LDR can enhance the neuron activity in certain areas of the brain.
15. Chen Shali, Meng Qingyong, Liu Shuzheng. Early expression of proteins in murine thymocytes after whole-body irradiation with low-dose X-rays. Chin. J. Radiol. Med. Prot., 1996, 16(3):161-163.	Abstract Early expression of proteins in nuclear and cytosolic extracts of thymocytes was investigated in mice exposed to low-dose ionizing radiation by means of two-dimensional electrophoresis. It was found that there were 4 novel protein spots and 5 protein spots with increased density and 1 protein spot with reduced density in the nuclear fraction as well as 3 novel protein spots and 3 protein spots with increased density in the cytosolic fraction 4 hr after whole-body irradiation with 75 mGy X-rays. The implications of these early gene expression products are discussed.	Early protein expression in nuclear and cytosolic extracts of thymocytes in mice exposed to 75 mGy X-rays found: 4 novel protein spots, 5 protein spots with increased density, and 1 protein spot with reduced density, in the nuclear fraction, as well as 3 novel protein spots and 3 protein spots with increased density in the cytosolic fraction, 4 hr after WBI. These early gene expression products are discussed.
16. Zhang Ming, Chen Zhiyun, Liu Shuzheng. Effects of low dose irradiation on the splenic macrophage function in mice. J. N. Bethune Univ. Med. Sci. 1996, 22(2):131-133.	Abstract Low dose whole-body irradiation (WBI) was given to Kunming mice with different doses (50~250 mGy) of X-rays. The dose rate was 12.5 mGy/min. The functional changes of macrophages in the immune system were observed. It was found that the low dose irradiation may enhance the function of macrophages on the reaction of lymphocytes to Con A and increase the content of IL-1 in the macrophages, and that the inhibiting function of splenic macrophages to S180 tumor cells was enhanced.	Doses of 50~250 mGy of X-rays at 12.5 mGy/min to mice showed enhanced functions of macrophages in the immune system in the lymphocyte reaction to Con A; an increase in the IL-1 content in the macrophages; and enhanced inhibiting function of splenic macrophages to S180 tumor cells.
17. Mu Ying, Liu Shuzheng. Effect of whole-body irradiation with X-rays on apoptosis of thymocytes in mice. Chin. J. Radiol. Med, Prot., 1996, 16(5):296-298.	Abstract Radiation-induced apoptosis of thymocytes in mice was quantified by measuring the percentage of DNA fragmentation by fluorescence spectrophotometry, and qualitatively analyzed by agarose electrophoresis. The results showed that DNA fragmentation of thymocytes began to increase 2 hours after exposure to 4 Gy, reaching its peak value at 14 hours. After that the percentage of DNA fragmentation came down to about 50% of the peak value at 24 hours. It was found that the apoptosis could be induced by high dose irradiation. A typical "ladder pattern" appeared on agarose gel electrophoresis after 1-4 Gy irradiation. The pattern of fragmentation represents oligonucleosomes with approximately 180 bp and its multiples. The dose-effect relationship of DNA fragmentation as measured by fluorescence spectrophotometry after whole-body irradiation with 0.025-4.0 Gy showed a J-shape curve with significantly reduced apoptosis at low doses.	DNA fragmentation of thymocytes began to increase 2 hours after exposure to 4 Gy, reaching its peak value at 14 hours. DNA fragmentation came down to about 50% of the peak value at 24 hours. Apoptosis was induced by high dose irradiation. After 1-4 Gy irradiation, oligonucleosomes with approximately 180 base-pairs and its multiples were observed. The dose-effect relationship of DNA fragmentation after 0.025-4.0 Gy WBI showed a J-shape curve, with significantly reduced apoptosis at low doses.
18. Fu Hanqing, Li Xiuyi, Li Youjun, Liu Shuzheng. Whole-body low dose irradiation suppresses cancer cell dissemination in mice. Chin. J. Radiol. Med. Prot., 1996, 16(5):307-309.	Abstract Lewis lung carcinoma or B₁₆ melanoma cells were injected into the retrobulbar vein of mice 24 h after whole-body irradiation (WBI) with 50, 75, 100 or 150 mGy X-rays. The dissemination of the cancer cells as evaluated by counting the tumor nodules on the lung surface 14 d after injection was found to be markedly decreased in the irradiated mice as compared with the sham-irradiated control. In mice given 75 mGy WBI 24 h before injection of Lewis lung carcinoma cells the splenic NK cell activity and IL-2 secretion were found to be potentiated 2-6 days after irradiation in comparison with the sham-irradiated mice which received the same number of tumor cells. The results suggest that low dose radiation might suppress cancer cell dissemination via the enhancement of immune reactivity.	Tumor nodules on lung surfaces 14 d after injection of Lewis lung carcinoma or B₁₆ melanoma cells injected into mice 24 h after 50, 75, 100, or 150 mGy X-ray WBI, was markedly decreased vs. sham-irradiated controls. With 75 mGy WBI 24 h before injection, the splenic NK cell activity and IL-2 secretion were potentiated 2-6 days after irradiation vs. controls which received the same number of tumor cells. Low dose radiation may suppress cancer cell dissemination via enhancement of immune reactivity.
19. Xu Guizhen, Li Xiuyi, Gong Shouliang, Liu Shuchun, Liu Shuzheng. Effect of low dose radiation on function of peritoneal macrophages in mice. Chin. J. Radiol. Med. Prot., 1996, 16(2):93-95.	Abstract This study was undertaken to observe the effects of single whole body irradiation with 0, 0.05, 0.075, 0.15, 2.0 and 4.0 Gy of X-rays on the function of peritoneal macrophages from Kunming mice in engulfing and digestion of chicken red blood cells (CRBC). The results showed that the engulfing functions of macrophages on CRBC 3 and 5 days after irradiation with 0.05 and 0.075 Gy increased obviously and their digestive function after irradiation with 0.075 Gy was significantly higher than that in the 0 Gy group. However, their engulfing and digestive functions decreased after the irradiation with 2 and 4 Gy. These results suggest that low dose radiation can stimulate the function of nonspecific immunity while large dose radiation can inhibit it.	After single 0, 0.05, 0.075, 0.15, 2.0 and 4.0 Gy X-ray WBI on mice, engulfing functions on chicken red blood cells (CRBC) obviously increased 3 and 5 days after irradiation with 0.05 and 0.075 Gy, and their digestive function after 0.075 Gy was significantly higher, vs. 0 Gy. However, engulfing and digestive functions decreased after 2 and 4 Gy. LDR can stimulate the function of nonspecific immunity, while large dose radiation can inhibit it.
20. Sun Tiehua, Gong Shouliang, Zhang Ming, Liu Shuzheng. Effects of low dose radiation on CuZn-SOD, Se-GSH-Px activities of immune organs. J. N. Bethune Univ. Med. Sci., 1996, 22(2):111-112.	Abstract The present study was designed to observe the changes of CuZn-SOD and Se-GSH-Px activities of thymocytes and splenocytes after low dose X-irradiation in rats in vitro and in vivo. Both enzymes of splenocytes increased significantly 12 h after the irradiation with 300 or 500 mGy in vitro. CuZn-SOD activity of splenocytes also increase significantly 24 h after whole-body irradiation with 150~500 mGy. These results suggest that the increase of splenocyte antilipoperoxidase activity after the irradiation may be a protective response to radiation damage.	CuZn-SOD and Se-GSH-Px activities of thymocytes and splenocytes after X-ray LDR in rats, in vitro and in vivo, showed both enzymes of splenocytes increased significantly 12 h after 300 or 500 mGy in vitro. CuZn-SOD activity of splenocytes also increased significantly 24 h after whole-body irradiation with 150~500 mGy. The splenocyte anti-lipoperoxidase activity increase after LDR may be a protective response to radiation damage.
21. Liu Shuzheng, Zhang Yingchun, Mu Ying, Su Xu, Liu Jianxiang. Thymocyte apoptosis in response to low dose radiation. Mutat. Res., 1996, 358:185-191. (in English)	Abstract Thymocyte apoptosis was assessed by counting apoptotic bodies with flow cytometry (FCM) and measuring DNA fragmentation with fluorescence spectrophotometry (FSP). J-shaped dose-response curves were obtained after both whole-body irradiation (WBI) of mice and in vitro irradiation of EL-4 cells with doses ranging from 0.025 to 4 Gy X-rays. There was a significant reduction of apoptosis rate to below control level with doses within 0.2 Gy and a dose-dependent increase in apoptosis with doses above 0.5 Gy. When thymocytes were cultured 24 h after WBI with 75 mGy X-rays in complete RPMI 1640 medium, a reduction in apoptosis was observed in the course of incubation for 72 h, and the presence of Con A in the medium accentuated this reduction in a dose and time-dependent manner. The implications of these observations and the possible molecular mechanisms for future studies are proposed.	Thymocyte apoptosis resulted in J-shaped dose-response curves after both, WBI of mice, and in vitro X-rays of EL-4 cells from 0.025 to 4 Gy. Apoptosis was significantly reduced below controls for doses within 0.2 Gy; with a dose-dependent increase above 0.5 Gy. Thymocytes cultured 24 h after 75 mGy X-rays, apoptosis was reduced over 72 h. Con A in the medium accentuated this reduction in a dose and time-dependent manner. Implications, and possible molecular mechanisms for future studies, are proposed.
22. Liu Shuzheng, Wan Hong, Chen Shali, Su Xu. Molecular changes related to the stimulatory effect of low dose radiation on immunity. J. N. Bethune. Univ. Med. Sci., 1996, 22(6):559-565. (in English)	Abstract It is first reported in the present paper that whole-body irradiation (WBI) of mice with 75 mGy X-rays could up-regulate the expression of Bcl-2 and increase the ratio of Bcl-2 to BAX in the immune organs. Meanwhile p53 expression was down-regulated after WBI with 75 mGy and up-regulated after WBI with 2 Gy X-rays. These experimental data give support at the molecular level to the previous finding of the J-shaped dose-effect curve of thymocyte apoptosis in which the percentage of DNA fragmentation and apoptotic bodies were reduced after low dose radiation (LDR). The changes in Bcl-2 expression after LDR were preceded by a rise in transcription of c-fos mRNA and expression of c-Fos protein in the immune organs. An increased binding activity of CREB, NF-kappaB and AP-1 to the nuclear extracts of the thymus and spleen was also observed after LDR. The transcription level of the POMC gene was down-regulated in the hypothalamus accompanied by an up-regulation of its transcription in the immune organs following LDR. These molecular changes give support to our previous reports on the stimulation of the immunologic functions at the cellular level and the down-regulation of the function of the hypothalamic-pituitary- adrenocortical axis at the systemic level after LDR.	75 mGy X-ray WBI of mice up-regulate Bcl-2 expression, and increase the Bcl-2/BAX ratio, in the immune organs. Meanwhile, p53 expression was down-regulated at 75 mGy X-ray, but up-regulated with 2 Gy X-rays. This supports, at the molecular level, the J-shaped dose-effect curve of thymocyte apoptosis in which DNA fragmentation and apoptotic bodies are reduced after LDR. Bcl-2 expression changes after LDR were preceded by a rise in transcription of c-fos mRNA, and expression of c-Fos protein in the immune organs. Binding activity of CREB, NF-kappaB, and AP-1 to the nuclear extracts of the thymus and spleen was increased after LDR. The POMC gene transcription level was down-regulated in the hypothalamus, with an up-regulation of its transcription in the immune organs, following LDR. These molecular changes support our previous reports on stimulating the immunologic functions at the cellular level, and the down-regulation of the function of the hypothalamic-pituitary- adrenocortical axis at the systemic level, after LDR.
23. Sun Chengwen, An Gang, Zhong Guogan, Zhan Shu, Jiang Yang, Liu Shuzheng, Zhang Yingchun. Effect of low dose X-rays on Ca²⁺-activated K⁺ channels in mouse thymic lymphocytes. Chin. J. Radiol. Med. Prot., 1996, 16(3):154-156.	Abstract The effect of low dose X-rays on Ca²⁺-activated K⁺ channels [K_(Ca)] in mouse thymic lymphocytes was observed using the cell-attached configuration of patch clamp technique. It is shown that low dose X-rays can elevate the open times and open-state probabilities of K_(Ca) channels, without apparent influence on the current flowing through the channels. After 3 min exposure of lymphocytes to Con A the open-state probabilities of K_(Ca) channels in the irradiated group were higher than those in the control group. It was observed that from 4 to 24 h after irradiation the activity of K_(Ca) channels increased with time. K_(Ca) channels are important in the molecular mechanism of immunoenhancement following low dose irradiation.	Low dose X-rays on Ca²⁺-activated K⁺ channels [K_(Ca)] in mouse thymic lymphocytes elevated the open times and open-state probabilities of K_(Ca) channels, without apparent influence on the current flowing through the channels. After 3 min exposure of lymphocytes to Con A, the open-state probabilities of K_(Ca) channels in the irradiated group were higher vs. the control group. From 4 to 24 h after irradiation, the activity of K_(Ca) channels increased with time. K_(Ca) channels are important in the molecular mechanism of immuno-enhancement following LDR.
24. Su Xu, Zhang Yingchun, Wan Hong, Liu Shuzheng. Effects of low dose radiation on differentiation, activation and apoptosis of thymocytes in mice. Chin. J. Radiol. Med. Prot., 1997, 17(3):162-165.	Abstract Objective: To elucidate the possible mechanism of immunoenhancement after low dose radiation (LDR), the differentiation, activation and apoptosis of thymocytes following low dose irradiation were studied. Method: Kunming mice were whole-body irradiated (WBI) with low dose X-rays. The expressions of CD4, CD8, TCR, CD3, IL-2R, [Ca²⁺]_i , Bcl-2, Bax and apoptosis of thymocytes were analyzed by flow cytomerty. Results: It was found that the ratio of T_H/T_s showed no significant changes after LDR. Thymocyte apoptosis was not increased after LDR. The increase of Bcl-2/Bax ratio after LDR might be one of its mechanisms. LDR could expedite the process of differentiation of, and facilitate the signal transduction in, thymocytes. Conclusion: The results indicate that the mechanism of immunoenhancement might be related to the expedition of the maturation, differentiation and activation of thymocytes, thus up-regulating the capability of supplying more mature T lymphocytes to the periphery by the thymus after LDR.	In mice, after X-ray WBI, CD4, CD8, TCR, CD3, IL-2R, [Ca²⁺]_i , Bcl-2, Bax expressions, and apoptosis of thymocytes, found: no significant changes in the T_H/T_s ratio; that thymocyte apoptosis was not increased; and that the Bcl-2/Bax ratio was increased, which may be one of its mechanisms. LDR could expedite differentiation of, and facilitate the signal transduction in, thymocytes. The immuno-enhancement mechanism may be related to expediting the maturation, differentiation, and activation of thymocytes, thus up-regulating the supply of more mature T lymphocytes to the periphery by the thymus after LDR.
25. Su Xu, Wan Hong, Liu Shuzheng. The effects of p53 and Bcl-2/Bax on apoptosis of thymocytes induced by ionizing radiation. J. Radiat. Res. Radiat. Proces., 1997, 15(2):119-122.	Abstract Kunming mice were whole-body irradiated (WBI) with 75 mGy and 2 Gy X-rays. The expression of p53, Bcl-2 and Bax proteins was analyzed with flow cytometry. It was found that the expression of p53 protein showed significant decrease (p<0.005) 24 hours after WBI with 75 mGy X-rays and significant increase (p<0.005) after WBI with 2 Gy X-rays. The ratio of Bcl-2/Bax was significantly increased (p<0.05) 24 hours after WBI with 75 mGy X-rays and showed no significant change after WBI with 2 Gy. The change in expression of p53 and Bcl-2/Bax ratio after WBI with 75 mGy and 2 Gy X-rays may give partial explanation to the inhibitory effect of low dose radiation on thymocyte apoptosis. The results suggested that p53 and Bcl-2/Bax play an important role on apoptosis of thymocytes induced by ionizing radiation.	In mice with X-ray WBI, p53 protein expression significantly decreased (p<0.005) 24 hours after 75 mGy, and significantly increased (p<0.005) after 2 Gy. The Bcl-2/Bax ratio was significantly increased (p<0.05) 24 hours after 75 mGy, with no significant change after 2 Gy. The p53 and Bcl-2/Bax ratio expression changes after 75 mGy and 2 Gy X-rays may partially explain the inhibitory effect of LDR on thymocyte apoptosis; and p53 and Bcl-2/Bax may play an important role in apoptosis of thymocytes induced by ionizing radiation.
26. Su Xu, Liu Shuzheng, S. Aizawa, H. Ohyama, T. Yamada. Influence of dose rate on radiation hormesis with low dose exposure. J. N. Bethune Univ, Med. Sci., 1997, 23(6):582-584.	Abstract In order to explore the influence of dose rate on radiation hormesis after low dose irradiation, Balb/c mice were irradiated at a same total dose with dose rates of 12.7 mGy/min and 0.2 Gy/min. The results showed that different biological effects were induced by different dose rates at the same total dose. The response of splenic lymphocytes to Con A assessed by ³H-TdR incorporation was increased after irradiation with a dose rate of 12.7 mGy/min, which is especially marked following total doses of 76.7 mGy and 105.5 mGy (p<0.01). However, the response of splenic lymphocytes to Con A showed no significant changes after irradiation with a dose rate of 0.2 mGy/min at the same total dose. The result indicated that low dose radiation hormesis could not be induced by high dose rate X-rays.	Mice irradiated at a same total dose increased ³H-TdR incorporation in splenic lymphocytes exposed to Con A at a dose rate of 12.7 mGy/min, which was especially marked after 76.7 mGy and 105.5 mGy (p<0.01); but there was no significant change at 0.2 mGy/min. LDR hormesis may not be induced by high dose-rate X-rays.
27. Zhang Ying, Liu Shuzheng. Low dose radiation reduces the immunosuppressive effect of cytotoxic agents on tumor-bearing mice. J. N. Bethune Univ. Med. Sci., 1997, 23(5):466-468.	Abstract In order to study the effect of whole body irradiation (WBI) with low dose X-rays in combination with mitomycin C (MMC) on the immune functions of tumor-bearing mice, we used C57BL/6 mice implanted with Lewis lung carcinoma as an experimental animal model. The results showed that 12 hours after 3.0 mg/kg MMC I.P. administration, the spontaneous incorporation of ³H-TdR into thymocytes, the reaction of splenocytes to Con A, the splenic production of IL-2 as well as the cytotoxic activities of natural killer cells (NK) and lymphokine activated killer cells (LAK) were markedly decreased. When WBI with 75 mGy X-rays was given 6 hours before MMC treatment, the above immune parameters significantly increased, as compared with those in mice with MMC treatment alone. The results implicated that WBI with low dose X-rays before chemotherapy could partly antagonize the immunosuppressive effect of MMC.	In mice implanted with Lewis lung carcinoma, 12 hours after 3.0 mg/kg mitomycin C (MMC) I.P. administration, spontaneous incorporation of ³H-TdR into thymocytes, the reaction of splenocytes to Con A, the splenic production of IL-2, as well as the cytotoxic activities of natural killer cells (NK) and lymphokine-activated killer cells (LAK), were markedly decreased. 75 mGy X-ray WBI 6 hours before MMC significantly increased these immune parameters vs. MMC treatment alone. LDR X-ray WBI before chemotherapy could partly antagonize MMC immunosuppressive effects.
28. Zhang Ying, Liu Shuzheng. Enhanced antitumor effect and mechanism of chemotherapy combined with low dose radiation. J. Radiat. Res. Radiat. Proces., 1997, 15(3):178-182.	Abstract It is well known that whole body irradiation (WBI) with low dose X-rays could improve the function of the immunological system and the antitumor efficacy of local large dose irradiation. In order to study the adjuvant effect of WBI with low dose on the tumor suppressive effect of chemotherapy, 6 hours before mitomycin C or cyclophosphamide I.P. administration, WBI with 75 mGy was given to C57BL/6 mice bearing Lewis Lung carcinoma. It was found that WBI with 75 mGy X-rays could markedly enhance the suppressive effect of chemotherapy on tumor growth and significantly increase some immunological parameters related to tumor killing. The results suggested that WBI with 75 mGy X-rays could reduce the immunological damage of tumor-bearing mice caused by chemotherapy and enhance the antitumor efficacy of cytotoxic agents.	Well-known improved immunological function, and anti-tumor efficacy, of local large dose irradiation by low dose X-rays, used 75 mGy X-ray WBI 6 hours before mitomycin C or cyclophosphamide I.P. administration to mice bearing Lewis lung carcinoma. The chemotherapy suppressive effect on tumor growth was markedly enhanced; and some immunological parameters related to tumor killing were significantly increased. Immunological damage to tumor-bearing mice caused by chemotherapy could be reduced, and the anti-tumor efficacy of cytotoxic agents enhanced.
29. Fu Hanqing, Li Xiuyi, Chen Yubing, Zhang Yingchun, Liu Shuzheng. Mechanism of suppressive effect of low dose radiation on cancer cell dissemination in mice. J. Radiat. Res. Radiat. Proces., 1997, 15(1):40-43.	Abstract In this paper, influence of low dose radiation on immunity in C57BL/6 mice implanted with cancer cells was studied. In mice given 75 mGy WBI 24 h before injection of Lewis lung carcinoma cells or B₁₆ melanoma cells, the percentage of S-phase thmocytes and CD³⁺ thymocytes, the splenic NK cell activity, IL-2 secretion and IFN-gamma secretion were found to be potentiated 2~8 days after irradiation in comparison with the sham-irradiated mice. The results suggest that low dose radiation might suppress cancer cell dissemination via the enhancement of immune reactivity.	In mice given 75 mGy X-ray WBI 24 h before injection of Lewis lung carcinoma cells, or B₁₆ melanoma cells, S-phase thymocytes and CD³⁺ thymocytes, the splenic NK cell activity, IL-2 secretion, and IFN-gamma secretion, were potentiated 2~8 days after irradiation vs. sham-irradiated mice. Low dose radiation may suppress cancer cell dissemination via the enhancement of immune reactivity.
30. Gong Shouliang, Liu Jianxiang, Liu Shuchun, Zhang Yingchun, Liu Shuzheng. Effect of splenocyte extracellular fluid irradiated with low dose X-rays on thymocyte apoptosis after larger dose X-irradiation in mice. J. Radiat. Res, Radiat. Proces., 1997, 15(1):36-39.	Abstract The splenocytes were cultured with Con A for 48 h in vitro 24 h after whole-body irradiation (WBI) with 75 mGy X-rays to mice. The extracellular fluid of the splenocytes decreased the thymocyte apoptosis in vitro 24 h after WBI with 2 Gy X-rays in mice, especially decreased significantly 72 h after the thymocyte culture (P<0.05). Meantime, the CD 25 (IL-2 receptor) expression of the splenocytes (P<0.01) and its IFN-gamma secretion (P<0.05) were enhanced significantly. The results suggest that low dose radiation changes the microenvironment of immune organs and the process of their signal transduction leading to the enhancement of immune functions with acceleration of the maturation and differentiation of immune cells and reduction of their apoptosis.	24 h after 75 mGy X-rays WBI to mice, for splenocytes cultured with Con A for 48 h in vitro, the extra-cellular fluid of the splenocytes decreased the thymocyte apoptosis in vitro 24 h after 2 Gy X-rays, with especially significant decrease at 72 h (P<0.05). Also significantly enhanced were the CD 25 (IL-2 receptor) expression of the splenocytes (p<0.01), and its IFN-gamma secretion (p<0.05). LDR may change the microenvironment of immune organs and the process of their signal transduction, enhancing immune functions by accelerating the maturation and differentiation of immune cells, and reducing their apoptosis.
31. Zhang Ying, Sun Yimin, Li Xiuyi, Mu Ying, Liu Shuzheng. An experimental study on the enhanced macrophage (M#) function in tumor-bearing mice treated with low dose radiation. J. Radiat. Res. Radiat. Proces., 1998, 16(4):249-252.	Abstract C57BL/6J mice implanted with Lewis lung carcinoma cells in the right thigh were used as an experimental animal model and whole body irradiation (WBI) with 75 mGy X-rays was given at the 10th day after tumor implantation. We detected the cytostasis function of peritoneal macrophages of the mice (with the method of ³H-TdR incorporation assay) and the levels of TNF-alpha and IL-1beta mRNA transcription (with method of in situ hybridization) 18 hours after irradiation. The experiment showed that the cytostasis function of the peritoneal macrophages of irradiated mice was significantly increased as compared with that of the sham-irradiated mice (irradiated mice: 79.9±4.2%, sham-irradiated mice : 52.9±8.1%, p<0.01). The levels of TNF-alpha and IL-1-beta mRNA transcription were quantitatively measured with a scanning densitometry and the data showed that both the TNF-alpha and IL-1-beta mRNA transcriptional levels of peritoneal macrophages of irradiated mice were much higher than those of sham-irradiated mice (p<0.01). The results mentioned above suggested that low dose radiation could markedly enhance the macrophage function in tumor-bearing mice and the enhanced macrophage function played an important role in the process of immunoenhancement and antitumor immune reaction induced by low dose radiation.	Mice implanted with Lewis lung carcinoma cells in the thigh, with 75 mGy X-rays WBI 10 d after implantation, had significantly increased cytostasis function of peritoneal macrophages vs. sham-irradiated mice (p<0.01); and TNF-alpha and IL-1beta mRNA transcription levels were much higher (p<0.01), 18 hours after irradiation. LDR may markedly enhance the macrophage function in tumor-bearing mice, with the enhanced macrophage function important in immuno-enhancement and anti-tumor immune reaction.
32. Zhang Ying, Lu Zhe, Li Xiuyi, Liu Shuzheng. Influence of low dose radiation on the pulmonary metastasis of Lewis lung carcinoma in mice. J. N. Bethune Univ. Med. Sci., 1998, 24(6): 559-562. (in English)	Abstract Objective: This paper investigated the influence of whole body irradiation (WBI) with low dose radiation (LDR) on the pulmonary metastasis of implantable tumor. Methods: The experiment was performed by the use of C57BL/6J mice bearing Lewis lung carcinoma as an experimental animal model. Ten d after tumor implantation, the tumor-bearing mice were given treatments as follows (1) sham-irradiated control; (2) 2 times 75 mGy X-rays WBI at 3 d interval; (3) 4 times 75 mGy X-rays WBI at 3 d intervals;(4) single 3.0 mg/kg MMC I.P. administration alone; (5) pre-exposure with 75 mGy X-rays WBI 6 h before 3.0 mg/kg MMC chemotherapy. 12 h after chemotherapy, some of the mice in groups (1), (4) and (5) were decapitated to detect the phagocytic function of peritoneal macrophages and the cytotoxic activity of natural killer cells (NK) in the spleen twenty-one d after tumor implantation, all the mice were sacrificed to count the number of lung metastatic foci. Results: MMC chemotherapy alone could not significantly reduce the number of lung metastatic foci (sham-irradiated control: 41.7, MMC chemotherapy alone: 33.8, P>0.05), while the number of lung metastatic foci in the group that was pre-exposed with 75 mGy X-rays WBI (20.3) was much fewer than that in the group with MMC chemotherapy alone (P<0.05). The number of lung metastatic foci in mice treated with 4 times 75 mGy X-rays WBI (23.5) was much fewer than that of sham-irradiated control (P<0.01), while the number of lung metastatic foci in mice treated with 2 times 75 mGy WBI (39.4) had a tendency of reduction, having no statistical significance (P>0.05). The results of the detection of immunological parameters demonstrated that MMC chemotherapy decreased the level of macrophage and NK cell function while pre-exposure with 75 mGy X-rays WBI could partly antagonize the immune suppression of MMC chemotherapy (P<0.05). Conclusion : Pre-exposure with 75 mGy X-rays WBI could reduce the immune suppressive effect of MMC and enhance the anti-metastatic effect of MMC chemotherapy; 4 times 75 mGy WBI could also decrease the metastasis of Lewis lung carcinoma.	C57BL/6J mice implanted with Lewis lung carcinoma were treated after 10 d as: (1) Sham-irradiated control. (2) 2 x 75 mGy X-rays WBI at 3 d interval. (3) 4 x 75 mGy X-rays WBI at 3 d intervals. (4) Single 3.0 mg/kg MMC I.P. chemotherapy alone. (5) Pre-exposure with 75 mGy X-rays WBI 6 h before 3.0 mg/kg MMC chemotherapy. The phagocytic function of peritoneal macrophages, and the cytotoxic activity of natural killer cells (NK) in the spleen, were measured at 12 h after MMC in some (1), (4) and (5) mice. Lung metastatic foci were counted at 21 d after implantation. MMC chemotherapy alone did not significantly reduce lung metastatic foci (p>0.05 vs. control); but they were much reduced by pre-exposure with 75 mGy vs. MMC alone (p<0.05); and 4 x 75 mGy was much reduced vs. sham-irradiated control (p<0.01); and 2 x 75 mGy had a tendency of reduction, but not statistically significant (p>0.05). Immunological parameters showed MMC decreased macrophage level and NK cell function; while 75 mGy pre-exposure could partly antagonize the immune suppression of MMC (p<0.05). 75 mGy pre-exposure could reduce the MMC immune suppressive effect, and enhance the anti-metastatic effect of MMC chemotherapy; and 4 x 75 mGy could decrease Lewis lung carcinoma metastasis.
33. Zhang Ying, Sun Yimin, Li Xiuyi, Mu Ying, Liu Shuzheng. Low dose radiation increases the mRNA transcriptional levels of IL-1beta and TNF-alpha in peritoneal macrophages of tumor-bearing mice. J. N. Bethune Univ. Med. Sci., 1998, 24(6):565-567.	Abstract Objective: To investigate the effect of low dose radiation (LDR) on the mRNA transcriptional levels of IL-1beta and TNF-alpha in peritoneal macrophages of tumor-bearing mice. Methods: C57BL/6J mice implanted with Lewis lung carcinoma cells in the right thigh were used as an experimental animal model, 75 mGy X-rays whole body irradiation (WBI) was given at the 10th day after tumor implantation and macrophages were obtained from peritoneal cavity with PBS washing 18 hours after irradiation and adherent cells were collected for observation. We detected the mRNA transcriptional levels of IL-1beta and TNF-alpha by the method of in situ bybridization histoimmunochemistry. The results were quantitatively measured by a scanning densitometry in assessment of the mean optical density (MOD). Results: The positive granules stained in blue-purple color were more frequent and with a deeper color in the macrophages of irradiated mice than in those of sham-irradiated mice. The MOD of IL-1beta and TNF-alpha positive granules in macrophages of irradiated mice were 0.285±0.005 and 0.272±0.012, while 0.216±0.005 and 0.204±0.005 respectively in macrophages of the sham-irradiated mice. The difference between the two groups was of statistical significance (P<0.01). Conclusion: LDR could significantly increase the transcriptional levels of IL-1brta and TNF-alpha in peritoneal macrophages of tumor-bearing mice and potentiate the direct tumor-killing and immune regulatory effects of IL-1beta and TNF-alpha.	Mice with Lewis lung carcinoma cells implanted in the thigh, and 75 mGy X-rays WBI the 10th day after implantation, macrophages 18 hours after irradiation had mRNA transcriptional levels of IL-1b and TNF-a differences that were statistically significant (p<0.01) vs. sham-irradiated controls. LDR could significantly increase the transcriptional levels of IL-1b and TNF-a in peritoneal macrophages of tumor-bearing mice, and potentiate the direct tumor-killing, and immune regulatory effects, of IL-1b and TNF-a .
34. Chen Yubing, Fu Hanqing, Lu Zhe, Li Xiuyi, Liu Shuzheng. Influence of low dose X-rays on tumor-suppressive effect of local high dose irradiation in tumor-bearing mice. J. N. Bethune Univ. Med. Sci., 1998, 24(6):568-570.	Abstract Objective: To study the influence of low dose radiation (LDR) on tumor-suppressive effect caused by local high dose irradiation (LHDI). Methods: Kunming mice implanted subcutaneously with S 180 ascites Sarcoma cells were used as an experimental tumor model. The tumor-bearing mice were exposed to whole body irradiation (WBI) with doses of 50, 75, 100 and 150 mGy X-rays 12 h or 24 h before LHDI with doses of 10 Gy or 2.5 Gy×4 and the tumor growth rate was observed. Results: The tumor-suppressive effect by LHDI was significantly enhanced by WBI with 50, 75 and 100 mGy as compared with that of LHDI alone. The enhancing effect of LDR given 12 h before LHDI was more marked than that of 24 h before LHDI. The enhancing effect of LDR before LHDI with a fractionation dose of 2.5 Gy×4 was more marked than that of a single dose of 10 Gy. Conclusion: It was demonstrated that LDR might enhance the tumor-suppressive effect of LHDI. The basic rules of this enhancing effect might have significance in clinical therapy.	Mice were implanted subcutaneously with S180 ascites Sarcoma cells and exposed to 50, 75, 100, and 150 mGy X-rays, WBI, 12 h or 24 h before local high-dose irradiation (LHDI) with doses of 10 Gy or 2.5 Gyx4. The LHDI tumor-suppressive effect was significantly enhanced at 50, 75 and 100 mGy compared to LHDI alone. The LDR enhancing effect given 12 h before LHDI was more marked than that of 24 h before LHDI. The LDR enhancing effect before a fractionation dose of 2.5 Gyx4 was more marked than that of a single dose of 10 Gy. LDR might enhance the tumor-suppressive effect of LHDI. This enhancing effect might have significance in clinical therapy.
35. Zhang Ying, Li Xiuyi, Liu Shuzheng. Enhancement of tumor suppressive effect of cyclophosphamide on implanted tumor by low dose radiation. J. N. Bethune Univ. Med. Sci., 1998, 24(6):571-573.	Abstract Objective: To investigate the tumor suppressive effect of cyclophosphamide (CP) in combination with low dose radiation (LDR). Methods: C57BL/6J mice implanted with Lewis lung carcinoma cells in the right thigh were used as an experimental animal model. Four days after tumor implantation, the tumor size (in diameter of leg) was measured with a caliper 3 times per week to set up tumor growth curve. When the tumor diameter was 7 mm, 100 mg/kg CP I.P. administration and 75 mGy X-rays whole body irradiation (WBI) were given. The cytotoxic activities of splenic natural killer (NK) and lymphokine activated killer (LAK) cells as well as specific cytotoxic T lymphocyte (CTL) were detected by method of ³H-TdR release assay. Results: The tumor diameter in the mice treated with CP and LDR at different times after treatment was much smaller than that of the mice with CP chemotherapy alone (P<0.05~0.01). The cytotoxic activities of NK, LAK and specific CTL were significantly increased as compared with those of the mice with CP chemotherapy alone (P<0.05~0.01). Conclusion: LDR could markedly improve the tumor therapeutic efficacy of CP chemotherapy via the reduction of CP damage on the immune system and stimulation of the antitumor immune reactions in tumor-bearing mice.	Mice were implanted with Lewis lung carcinoma cells in the thigh, and tumor size was measured until 7 mm; then treated with 100 mg/kg cyclophosphamide (CP) I.P., and 75 mGy X-rays WBI. Tumor size with CP and LDR at different times was much smaller than with CP chemotherapy alone (p<0.05~0.01). Cytotoxic activities of splenic natural killer (NK), and lymphokine activated killer (LAK), cells, and specific cytotoxic T lymphocyte (CTL), were significantly increased vs. CP alone (P<0.05~0.01). LDR could markedly improve CP chemotherapy for tumor therapeutic efficacy by reducing CP damage on the immune system, and stimulating the anti-tumor immune reactions.
36. Liu Shuzheng. Low level environmental agents and adaptive response. Chin. J. Radiol. Med. Prot., 1998, 18(5):310-315.	Abstract The current status of research on the adaptive response induced by low level exposures to environmental agents is briefly described. Emphasis is given to the characteristics of the dose-response and time-response relationships of adaptive response induced by extremely low dose-rate ionizing radiation. Recent advances in the mechanistic studies of adaptive response to low level ionizing radiation are analyzed. A discussion is given to the outlook of application of the scientific data concerning the adaptive response induced by low level environmental agents. Suggestions are made for further research in this field.	Research status on adaptive response induced by low level exposures to environmental agents, especially characteristics of the dose-response and time-response relationships by extremely low dose-rate ionizing radiation, and advances in mechanistic studies, is described. The outlook to apply the scientific data is discussed, with suggestions for further research.
37. Xie Feng, Su Xu, Liu Shuzheng. Time course of intracellular free Ca²⁺ concentration changes in thymocytes after whole body irradiation with X-rays. Chin. J. Radiol. Med. Prot., 1998, 18(5):351-353.	Abstract Objective: The purpose of the present study was to look at the possible influence of whole body irradiation (WBI) with X-rays on the intracellular free Ca²⁺concentration [Ca²⁺]_iin thymocytes and to elucidate the possible molecular mechanism of immunoenhancement following low dose radiation (LDR). Method: [Ca²⁺]_i was assayed by fluorescence spectrophotometry after loading the thymocytes with a fluorescence probe (Fura-2AM). Result: It was found that [Ca²⁺]_i increased after WBI with 75 mGy X-rays, reaching its peak at 24 h and returning to control level within 72 h. Conclusion: The results indicate that LDR can promote signal transduction of T lymphocytes.	75 mGy X-ray WBI increased intracellular free Ca²⁺concentration [Ca²⁺]_iin thymocytes, reaching its peak at 24 h and returning to control level within 72 h, possibly influencing the molecular mechanism of immuno-enhancement following LDR. LDR can promote signal transduction of T lymphocytes.
38. Bai Ou, Liu Shuzheng, Mu Ying. Effect of low dose radiation on Th1 and Th2 of thymocytes and splenocytes in mice. Chin. J. Radiol. Med. Prot., 1998, 18(2):106-109.	Abstract Objective: To elucidate the possible mechanism of activation of helper T cells after low dose radiation (LDR) exposure, the influence of whole-body irradiation (WBI) with 75 mGy X-rays on Th1 and Th2 was studied. Method: Mice were irradiated at a dose rate of 12.5 mGy/min, and IFN-g and IL-6 mRNA levels of the thymocytes and splenocytes were analyzed by dot blot and Northern blot hybridization. Result: It was found that IFN-g and IL-6 mRNA significantly increased after WBI with 75 mGy X-rays. Conclusion: The gene induction of cytokine profile after LDR indicates that activation of both Th1 and Th2 subtypes may be involved in the stimulation of immune functions by LDR.	To study the mechanism of activation of helper T cells by LDR, 75 mGy X-ray WBI of mice at a dose rate of 12.5 mGy/min, in Th1 and Th2, IFN-g and IL-6 mRNA levels of the thymocytes and splenocytes were significantly increased. The gene induction of cytokine profile after LDR indicates that activation of both Th1 and Th2 subtypes may be involved in stimulating immune functions by LDR.
39. Zhao Yong, Gong Shouliang, Liu Shuzheng. Immune regulative effect of low dose radiation on local microenvironment of immune organs. Chin. J. Pathophys., 1998, 14(1):1-5.	Abstract AIM and METHOD: To observe the effects of serum, thymocyte and splenocyte extracellular fluids (EFT, EFS) on immune functions 24 h after whole-body irradiation with 75 mGy X-rays on Kunming male mice. RESULTS: The inhibitory effect of irradiated murine serum on the response of the splenocytes to Con A was lower than that of normal murine serum, and the inhibitory effect of irradiated EFT (EFS) on thymocyte spontaneous proliferation (response of splenocytes to Con A), especially that of the fraction with MW < 10 kD of EFT (EFS), was also lower than that of normal EFT (EFS). Irradiated EFT or EFS was divided into two protein peaks through the Sephadex G 100 filtration. The first peak was higher and the second peak was lower than that of normal EFT or EFS, and the inhibitory effect of second peak on immune function was much lower than that of normal EFT or EFS. CONCLUSION: The local microenvironment of immune organs altered by low dose radiation leading to the enhancement of immune functions may be related to the changes of humoral factors.	24 h after 75 mGy X-rays WBI on mice, the inhibitory effect of irradiated murine serum on the splenocyte response to Con A was reduced vs. normal murine serum. Also, the inhibitory effect of irradiated thymocyte and splenocyte extracellular fluids (EFT, EFS) on thymocyte spontaneous proliferation (and splenocyte response to Con A), was reduced vs. normal EFT (EFS). For irradiated EFT or EFS divided into two protein peaks, the first peak was higher, and the second was lower, vs. normal EFT or EFS. The second peak inhibitory effect on immune function was much lower vs. normal EFT or EFS. The local microenvironment of immune organs altered by LDR leading to enhanced immune functions may relate to humoral factor changes.
40. Su Xu, Wan Hong, Liu Shuzheng. Effect of low dose radiation on expression of apoptosis- related gene products. Chin. J. Radiol. Med. Prot., 1998, 18(2):77-79.	Abstract Objective: To study the expression of p53, bcl-2 and bax proteins in thymocytes following low dose radiation (LDR) and to explore the molecular mechanism of radiation hormesis and dose-effect "J" shape curve of apoptosis induced by radiation. Methods: Kunming mice were subjected to whole-body irradiation (WBI) with 75 mGy X-rays. The expression of p53, bcl-2 and bax proteins was analyzed by flow cytometry 24 hours after irradiation. Results: It was found that the expression of p53 protein significantly decreased (P<0.005). The expression of bcl-2 protein showed slight but not significant increase, while expression of bax protein showed slight but not significant decrease. However, the ratio of bcl-2/bax was significantly increased (P<0.05). Conclusion: The changes in expression of p53 and bcl-2/bax ratio after WBI with LDR indicate that p53 and bcl-2/bax ratio might play an important role in gene regulation on apoptosis induced by radiation. The results may provide data for elucidating the molecular mechanism of radiation hormesis and dose-effect "J" shape curve of apoptosis induced by radiation.	After 24 hours, from mice subjected to 75 mGy X-rays WBI, expression in thymocytes of p53 protein significantly decreased (p<0.005); bcl-2 protein showed slight but not significant increase, while bax protein showed slight but not significant decrease. However, the bcl-2/bax ratio was significantly increased (p<0.05). p53 and bcl-2/bax ratio might play an important role in gene regulation on apoptosis induced by radiation, which may elucidate the molecular mechanism of radiation hormesis and dose-effect "J" shape curve of apoptosis induced by LDR.
41. Xie Feng, Su Xu, Liu Shuzheng. Effect of Low dose radiation on [Ca²⁺]_i in thymocytes. J. Radiat. Res. Radiat. Proces., 1998, 16(1):42-44.	Abstract Kunming mice were whole body irradiated with different doses of X-rays. Changes of cytosolic-free calcium concentration in thymocytes were measured using Fura-2AM as fluorescent probe. It was found that [Ca²⁺]_i increased 24 h after WBI with 75~100 mGy X-rays and the increase in [Ca²⁺]_i of thymocytes was found to be more marked in the presence of Con A stimulation. The results indicate that low dose radiation can promote signal transduction of T lymphocytes.	24 h after 75~100 mGy X-rays WBI of mice, cytosolic-free calcium [Ca²⁺]_i concentration in thymocytes increased, and the increase was more marked in the presence of Con A stimulation. LDR can promote signal transduction of T lymphocytes.
42. Chen Shali, Liu Shuzheng. Activation of transcription factor CREB and NF-kappaB in murine immune cells after WBI with 75 mGy X-rays. J. Radiat. Res. Radiat. Proces., 1998, 16(1):45-49.	Abstract Alterations in transcription factors NF-kappaB, CREB, AP1, SP1, GRE and OCT1 binding to specific known promoter DNA consensus sequences of immune cells from irradiated and sham-irradiated mice 4 hours after whole body irradiation (WBI) with 75 mGy X-rays were investigated with gel mobility shift assay. Increased binding to NF-kappaB and CREB consensus sequence was found with nuclear extracts prepared from thymocytes and splenocytes of irradiated versus sham-irradiated mice. Protein binding to the NF-kappaB consensus sequence by nuclear extracts derived from irradiated mice was 5-fold in splenocytes and 4.3-fold in thymocytes higher than that from sham-irradiated. Competition with the cold oligonucleotide containing the consensus sequence for NF-kappaB resulted in loss of the shifted band at 25-fold excess concentration, indicating the specificity of the binding. DNA mobility shift assay using CREB consensus sequence showed 7-fold increase in splenocytes and 6-fold increase in thymocytes after low dose radiation (LDR). Competition assays using cold oligonucleotide containing the CREB site eliminated the shift band at 50-fold excess concentration. The binding of AP1 consensus sequence showed a 2-fold increase in thymocyte nuclear extracts after LDR. No changes in protein binding to SP1, GRE and OCT1 consensus sequences were noted. The results indicate that activation of selective transcription factors NF-kappaB, CREB and AP1 of the immune cells in mice occurred after LDR.	4 hours after 75 mGy X-rays WBI of mice, binding of transcription factors NF-k B and CREB to known promoter DNA consensus sequences of immune cells with nuclear extracts prepared from thymocytes and splenocytes was increased vs. sham-irradiated mice. Protein binding to the NF-k B consensus sequence by nuclear extracts was 5-fold higher in splenocytes and 4.3-fold higher in thymocytes. Competition with the cold oligonucleotide containing the NF-k B consensus sequence resulted in loss of the shifted band at 25-fold excess concentration, indicating the specificity of the binding. DNA mobility shift assay showed 7-fold increase in splenocytes and 6-fold increase in thymocytes. Competition assays eliminated the shift band at 50-fold excess concentration. The binding of AP1 consensus sequence showed a 2-fold increase in thymocyte nuclear extracts. Protein binding to transcription factors SP1, GRE and OCT1 consensus sequences were not changed. LDR activated selective transcription factors NF-k B, CREB and AP1 of the immune cells in mice.
43. Chen Shali, Meng Qingyong, Liu Shuzheng. Alteration in transcription factor binding in murine thymocytes after low dose radiation. J. N. Bethune Univ. Med. Sci., 1998, 24:115-116.	Abstract Objective: To study the effect of low dose radiation on gene transcription regulation of murine thymocytes. Methods: Alteration in transcription factor binding in murine thymocytes 4 h after whole body irradiation (WBI) with 75 mGy X-rays was investigated with gel mobility shift assay. Results: Increased binding to CREB, NF-kappaB and AP1 consensus sequences was found with nuclear extracts prepared from thymocytes of irradiated versus sham-irradiated mice. Binding to the CREB, NF-kappaB and AP1 consensus sequences by nuclear extracts derived from irradiated mice was 6-fold, 4.3-fold and 2-fold higher than that from sham-irradiated respectively. The present report demonstrates that WBI with 75 mGy X-rays is capable of increasing expression of CREB, NF-kappaB and AP1 in murine thymocytes. Competition with the cold olignucleotide containing the consensus sequences for CREB and NF-kappaB resulted in loss of the shifted band, indicating specific binding. Conclusion: X-ray activation of select transcription factors, which bind certain consensus sites in promoters, may cause specific induction of gene transcription.	4 h after 75 mGy X-rays WBI in mice, increased binding to transcription factor CREB, NF-k B and AP1 consensus sequences with nuclear extracts prepared from murine thymocytes of irradiated vs. sham-irradiated mice, 6-fold, 4.3-fold and 2-fold higher vs. sham-irradiated mice respectively. 75 mGy X-rays WBI can increase expression of CREB, NF-k B and AP1 in murine thymocytes. Competition with the cold oligonucleotide containing the consensus sequences for CREB and NF-k B resulted in loss of the shifted band, indicating specific binding. X-ray activation of select transcription factors, which bind certain consensus sites in promoters, may cause specific induction of gene transcription.
44. Chen Shali, Meng Qingyong, Liu Shuzheng. Protein expression and tyrosine phosphorylation in murine immune cells after ionizing radiation. J. N. Bethune Univ. Med. Sci., 1998, 24(2):117-119.	Abstract Objective: To investigate alterations of protein expression and tyrosine phosphorylation in murine immune cells after low dose radiation. Methods: Change of protein expression in immune cells of mice 0~12 h after whole body irradiation with 75 mGy X-rays were observed with SDS-PAGE followed by densitometric scanning. Results: It is revealed that a Mr=28 000 protein increased gradually within 12 h and a Mr=43 000 protein increased in the thymocytes rapidly, reaching a maximum 2 h after irradiation. It was also observed that a Mr=43 000 protein and a Mr=32 000 protein increased in the splenocytes 2 h after irradiation. It is shown that tyrosine phosphorylation of Mr=28 000, Mr=32 000 and Mr=43 000 proteins appeared in the thymocytes after irradiation with immunoprecipitation and Western blotting using anti-phosphotyrosine McAb. Conclusion: These findings may have implications in the mechanism of immunoenhancement and adaptive response induced by low dose radiation.	0~12 h after 75 mGy X-rays WBI, in protein expression in immune cells of mice, a Mr=28 000 protein increased gradually within 12 h, and a Mr=43 000 protein increased in the thymocytes rapidly, reaching a maximum 2 h after irradiation. A Mr=43 000 protein and a Mr=32 000 protein increased in the splenocytes 2 h after irradiation. Tyrosine phosphorylation of Mr=28 000, Mr=32 000 and Mr=43 000 proteins appeared in the thymocytes after irradiation. These findings may have implications in defining the mechanism of immuno-enhancement and adaptive response induced by LDR.
45. Chen Shali, Liu Shuzheng. Activation of transcription factor CREB and NF-kappaB in mouse spleen by Low Dose Radiation. Prog. Biochem. Biophys., 1998, 25(2):147-150.	Abstract The effect of whole-body irradiation (WBI) on transcriptional regulation in mouse spleen was studied using gel electrophoresis mobility shift assay (EMSA) and oligonucleotide competitive inhibition analysis. Binding of nuclear protein extract from splenic cells to [gamma-³²P] ATP labeled CREB and NF-kappaB consensus sequences was found to be increased 4 h after WBI with 75 mGy X-rays, being 7 and 5 times higher, respectively, than that of the sham-irradiated control. Competitive inhibition analysis with excessive amount of unlabeled consensus sequences completely blocked the binding in corresponding EMSA, demonstrating the specificity of the reaction. The results suggest that low dose WBI could selectively activate the transcription factors CREB and NF-kappaB, which would induce specific gene transcription in the splenic cells leading to their functional activation.	Binding of nuclear protein extract from splenic cells to [g -³²P] ATP labeled transcription factors CREB and NF-k B consensus sequences increased 4 h after 75 mGy X-rays WBI, 7 and 5 times higher, respectively, vs. sham-irradiated control. Competitive inhibition completely blocked the binding, demonstrating the specificity of the reaction. Low dose WBI could selectively activate the transcription factors CREB and NF-k B, inducing specific gene transcription in the splenic cells leading to their functional activation.
46. Sun Yimin, Liu Shuzheng. Changes in mRNA level of TNF-alpha and IL-1beta in mouse peritoneal macrophages after whole-body X-irradiation. Radiat. Prot., 1998, 18(2):119-125.	Abstract In situ hybridization was used to examine the transcription level of TNF-alpha and IL-1beta in mouse peritoneal macrophages following whole-body irradiation (WBI) at different doses of X-rays. It was observed that the transcription level of TNF-alpha and IL-1beta in peritoneal macrophages reached its peak at 2 and 1 Gy, respectively, when examined 2 h after WBI. There was no constitutive expression for TNF-alpha mRNA in the macrophages and after WBI at doses from 0.075 to 2 Gy, a dose-dependent increase was induced in its expression. For IL-1beta, a moderate constitutive expression was shown in these cells and after WBI at doses between 0.025 and 1 Gy, its expression increased in a dose-dependent manner. WBI at 2 Gy caused more marked induction of TNF-alpha than that at 0.075Gy, with its peak value 2.76 times as high as that of the latter. Time course of the induction of these two genes after WBI at 2 and 0.075 Gy showed that the increase in their transcription lasted longer with the lower dose. The implications of these changes in the mechanism of hormesis for low dose radiation were discussed.	The TNF-a and IL-1b in peritoneal macrophages reached its peak at 2 and 1 Gy, respectively, 2 h after WBI. There was no constitutive expression for TNF-a mRNA in the macrophages and after 0.075 to 2 Gy WBI, a dose-dependent increase was induced in its expression. For IL-1b , a moderate constitutive expression was shown in these cells, and after WBI at 0.025 to 1 Gy, its expression increased in a dose-dependent manner. 2 Gy caused more marked induction of TNF-a vs. 0.075 Gy, with its peak value 2.76 times higher. The increase in their transcription lasted longer with 0.075 Gy. The implications to the LDR hormesis mechanisms are discussed.
47. Wan Hong, Liu Shuzheng. Effect of low dose radiation on POMC transcription level in mouse hypothalamus and immune organs. Chin. J. Radiol. Med. Prot., 1998, 18(3):145-147.	Abstract Objective: To disclose the changes in mRNA transcription level of POMC in the hypothalamus and immune organs after low dose radiation. Method: In situ hybridization was used to examine the changes of POMC mRNA transcription level in mouse hypothalamus and immune organs following whole body irradiation (WBI) with 75 mGy X-rays. Results: There was a basal expression of POMC mRNA in both the hypothalamus and immune organs. POMC mRNA-positive neurones were located in the arcuate nucleus of hypothalamus. WBI with 75 mGy X-rays could significantly down-regulate the POMC transcription level that was remarkable within 1 h and remained low in the observation period of 12 h. POMC transcription level in mouse immune organs increased with time within 8 h after irradiation and then began to decrease but still remained at a higher than normal level. The changes of POMC transcription level were more marked in the spleen than in other immune organs. Conclusion: These findings suggest that the immediate decrease of POMC transcription level in the hypothalamus might be the direct cause of the down-regulation of the hypothalamus-pituitary-adrenocortical axis after WBI with 75 mGy X-rays, accompanied with an increase in POMC transcription in immune organs.	POMC mRNA transcription level following 75 mGy X-rays WBI significantly down-regulated the POMC transcription level in mouse hypothalamus within 1 h, and remained low for the 12 h observation. POMC transcription level in mouse immune organs increased with time within 8 h, and then began to decrease, but remained at a higher than normal level. POMC transcription level changes were more marked in the spleen than in other immune organs. The immediate decrease of POMC transcription level in the hypothalamus might be the direct cause of the down-regulation of the hypothalamus-pituitary-adrenocortical axis after 75 mGy X-rays WBI, with an increase in POMC transcription in immune organs.
48. Gong Shouliang, Liu Shuchun, Zhang Yingchun, Liu Shuzheng. Adaptive response of thymocyte apoptosis and cell cycle progression induced by low dose radiation. J. Radiat. Res. Radiat. Proces., 1998, 16(3):150-152.	Abstract The adaptive response of thymocyte apoptosis and cell cycle progression induced by 75 mGy X-rays in mice were observed. The percentages of thymocyte apoptotic bodies (TAB) and cell cycle phase changes were examined with flow cytometry. It was found that the percentages of TAB increased, the percentages of S phase cells decreased and the percentages of G₀/G₁ and G₂+M phase cells increased after whole-body irradiation with 1.5 or 2.0 Gy in mice, all were statistically significant, as compared with sham-irradiated control. When the mice were irradiated with 75 mGy (inductive dose, D₁) 6 h before 1.5 or 2.0 Gy (challenge dose, D₂) exposure, the damaging effects of D₂ on thymocyte apoptosis and cell cycle progression were obviously reduced. Low dose radiation may induce the adaptive response of thymocyte apoptosis and cell cycle progression.	After 75 mGy X-rays WBI in mice, thymocyte apoptotic bodies (TAB) increased. In cell cycle progression, the percentages of S phase cells decreased, and the percentages of G₀/G₁ and G₂+M phase cells increased, after 1.5 or 2.0 Gy WBI in mice, all statistically significant vs. sham-irradiated control. 75 mGy 6 h before 1.5 or 2.0 Gy obviously reduced the damaging effects of 1.5 or 2.0 Gy on thymocyte apoptosis and cell cycle progression. LDR may induce the adaptive response of thymocyte apoptosis and cell cycle progression.
49. Li Xiuyi, Li Xiujuan, Zhang Ying, Lü Ze, Liu Shuzheng. Influence of low dose ionizing radiation on thymic lymphoma induced by carcinogenic dose radiation in C57BL/6J mice. Acad. Period. Abst. Chin., 1998, 4(11): 1406-1407.	Abstract The influences of low dose radiation (LDR) on carcinogenesis in mice were studied. The incidence of the thymic lymphoma (TL) in each group of mice irradiated with a different dose of whole body X-rays was determined by microscopic examination of the thymus 6 months after irradiation. With LDR of 25 mGy or 75 mGy 6 h or 12 h prior to carcinogenic dose (1.75 Gy × 4) of radiation, the occurrences of TL in mice was lower than that in mice subjected only to the carcinogenic dose radiation. The LDR could reduce the occurrence of TL induced by carcinogenic dose of radiation.	25 mGy or 75 mGy 6 h or 12 h prior to carcinogenic dose (1.75 Gy × 4) of radiation, thymic lymphoma (TL) incidence was lower vs. mice subjected only to the carcinogenic dose by examination of the thymus 6 months after irradiation. LDR could reduce the occurrence of TL induced by a carcinogenic dose of radiation.
50. Liu Shuzheng. Biological defense and adaptation induced by low dose radiation. Human & Ecological Risk Assessment (HERA), 1998, 4(5):1217-1254. (in English)	Abstract The present paper reviews recent experimental data obtained from studies on stimulation of immune functions and induction of cytogenetic adaptive response by low level radiation. An attempt is made to integrate recent observations in the author’s laboratory. Emphasis is given to the effects of single and chronic whole-body irradiation (WBI) with X-or g -rays. A schematic diagram of the interactions of the immune cells after low dose radiation is proposed to elucidate the possible cellular mechanism of the stimulatory effect of low dose radiation on immunity. Experimental data on the dose-effect relationship of induction of cytogenetic adaptive response in somatic and germ cells by single and chronic whole-body irradiation are presented. In the analysis of the molecular mechanism of the stimulatory effect of low dose radiation the activation of signal transduction pathways and induction of genes related to cell survival and proliferation are emphasized. The implications of the existing data are discussed and future investigations for the elucidation of possible common molecular basis of stimulation of biological defense and adaptation by WBI with low doses are suggested.	The author’s laboratory data on the stimulation of immune functions and induction of cytogenetic adaptive response by LDR, emphasizing single and chronic X-or g -ray WBI, are integrated; with a schematic diagram of immune cells interactions after LDR on the possible cellular mechanism of the LDR stimulatory effect on immunity; and dose-effect relationships inducing cytogenetic adaptive response in somatic and germ cells. The molecular mechanism of the stimulatory effect of LDR on the activation of signal transduction pathways and induction of genes are related to cell survival and proliferation. The implications are discussed, and future investigations on the possible common molecular basis of stimulating biological defense and adaptation by LDR WBI are suggested.
51. Gong Shouliang, Liu Shuchun, Liu Jianxiang, Zhang Yingchun, Liu Shuzheng. Adaptive response of thymocyte apoptosis induced by X-irradiation with 75 mGy. J. N. Bethune Univ. Med. Sci., 1998, 24(2):111-114. (in English)	Abstract Objective: in present study we observed the adaptive response of thymocyte apoptosis induced by low dose radiation (LDR). Methods: In the experiment the model of Kunming male mice with whole-body irradiation (WBI) was used. The inductive dose (D₁) was 75 mGy and the challenge dose (D₂) was 1.5 or 2.0 Gy. The time interval between D₁ and D₂ was 6 h. Results: The percentages of thymocyte apoptotic bodies (TAB) in D₁+D₂ group 18 h after WBI with D₂ were significantly lower than those in D₂ group (P<0.05). In addition, when the extracellular fluid of the splenocytes irradiated with 75 mGy was added to the thymocyte suspension irradiated with 2.0 Gy, the percentages of TAB after the incubation for 72 h were significantly lower than those in 2.0 Gy irradiated thymocytes (P<0.05). Conclusion: These results suggest that LDR (75 mGy) could change the external environment of immune cells, decrease the thymocyte apoptosis and induce an adaptive response of thymocyte apoptosis in the mice irradiated subsequently with larger dose (1.5 or 2.0 Gy) of X-rays.	The adaptive response of thymocyte apoptosis induced by LDR mice with WBI. A 75 mGy inductive dose (D₁) and a 1.5 or 2.0 Gy challenge dose (D₂) with 6 h between D₁ and D_2, the percentages of thymocyte apoptotic bodies (TAB) in the D₁+D₂ group 18 h after WBI with D₂ were significantly lower than those in D₂ group (P<0.05). When the extracellular fluid of the splenocytes irradiated with 75 mGy was added to the thymocyte suspension irradiated with 2.0 Gy, the percentages of TAB after the incubation for 72 h were significantly lower than those in 2.0 Gy irradiated thymocytes (p<0.05). LDR of 75 mGy could change the external environment of immune cells, decrease thymocyte apoptosis, and induce an adaptive response of thymocyte apoptosis in the mice irradiated subsequently with 1.5 or 2.0 Gy of X-rays.
52. Su Xu, Luo Can, Fu Shibo, Liu Jianxiang, Ju Guizhi, Liu Shuzheng. Effects of radiation on IL-2Ralpha expression of splenocytes in mice. J. Radiat. Res. Radiat. Proces., 1999, 17(1):48-51.	Abstract To elucidate the possible mechanism of immunoenhancement after low dose radiation (LDR). The dose-effect relationship of changes of IL-2Ralpha expression in splenocyte following low dose irradiation was studied. IL-2R expression was induced by Con A in vitro 24 hours after whole-body irradiation (WBI). The expression of IL-2R in splenocyte was analyzed by flow cytometry with direct immunofluorescence. It was found that the expression of IL-2R in splenocyte was significantly increased (P<0.05) 24 hours after WBI with doses of 50~500 mGy, in which the percentage of CD25 positive cells was significant higher than that in sham irradiated group, and the highest was in irradiated group with 50 mGy (P<0.01). The percentage of CD25 positive cells did not change significantly after WBI with 1.0~2.0 Gy (P>0.05). However, the percentage of CD25 positive cells decreased significantly after WBI with 4.0~6.0 Gy (P<0.05, P<0.01 respectively). The results indicate that LDR might enhance and stimulate the expression of IL-2R in splenocyte. The results are important for elucidating the mechanism of immunoenhancement after low dose radiation. The results following WBI with higher doses suggested that WBI with higher doses might suppress the expression of IL-2R in splenocytes.	IL-2Ra expression in splenocytes induced by Con A in vitro 24 hours after WBI was significantly increased (p<0.05) 24 hours after 50~500 mGy WBI. The percentage of CD25 positive cells was significantly higher vs. sham irradiated mice, the highest was at 50 mGy (p<0.01), with no significant change after 1.0~2.0 Gy (p>0.05), but with a significant decrease after 4.0~6.0 Gy (p<0.05, p<0.01 respectively). LDR might enhance and stimulate the expression of IL-2R in splenocytes, important to elucidate the mechanism of immuno- enhancement after LDR. WBI with higher doses may suppress the expression of IL-2R in splenocytes.
53. Zhang Ying, Lu Zhe, Li Xiuyi, Liu Shuzheng. The Anti-tumor effect of low dose radiation in combination with cytotoxic agent on the growth and metastasis of implanted tumor and the immune function in mice. Radiat. Prot., 1999, 19(2):127-131.	Abstract C57BL/6J mice implanted with Lewis lung carcinoma cells in the right thigh were used as an experimental animal model. When the tumor was 7 mm in diameter the tumor-bearing mice were treated as follows. For the chemotherapy group (CTG), an intraperitoneal injection of mitomycin C (MMC) at 3.0 mg/kg was given and for the adjuvant therapy group (ATG), a whole-body irradiation of 75 mGy X ray was added 6 hours before the injection of MMC. For both groups, the tumor growth curves were established. The immune function was examined 12 hours after treatment. 10 days after treatment, the tumor-bearing mice were sacrificed to count the lung metastatic colonies. The results show that in ATG, the tumor growth rate was obviously slower (P<0.05~0.01) and the number of lung metastatic colonies was less in number(P<0.01) in comparison with those in CTG and that all of the parameters of immune function for ATG were significantly higher than those for CTG. These results suggest that low dose radiation could enhance the anti-tumor effect of MMC therapy and that the hormesis effect on immune function induced by low dose radiation may be a possible mechanism.	When tumors were 7 mm in diameter in mice implanted with Lewis lung carcinoma cells, a chemotherapy group (CTG) received an intraperitoneal injection of mitomycin C (MMC) at 3.0 mg/kg, and an adjuvant therapy group (ATG) received 75 mGy X-rays WBI 6 h before MMC injection. The immune function at 12 hours after treatment for ATG were significantly higher vs. the CTG. At 10 d after treatment, the tumor-bearing mice were sacrificed to count the lung metastatic colonies. In ATG, the tumor growth rate was obviously reduced (p<0.05~0.01) and the number of lung metastatic colonies was lower (p<0.01), vs. the CTG. LDR could enhance the anti-tumor MMC therapy, and LDR-induced hormesis effects on immune function may be a mechanism.
54. Chen Shali, Cai Lu, Li Xiaokun, Liu Shuzheng. Low-dose whole-body irradiation induces alteration of protein expression in mouse splenocytes. Toxicol. Lett., 1999, 105(2) : 141- 152. (in English)	Abstract In previous studies, the stimulatory effect on immunological function and adaptive response in splenocytes were found after exposure of mice to low-dose whole-body irradiation (LD-WBI). Protein synthesis was found to be required for these responses. The present study, therefore, attempts to investigate the protein changes in mouse splenocytes after exposure to LD-WBI. Two-dimensional gel electrophoresis was used to show the alterations of proteins in nuclei, cytoplasm and extracellular fluid of the splenocytes at 4 h after mice exposed to 75 mGy X-rays. As compared to control, changed expressions of 20, 15 and 6 proteins, in sizes ranging from 10 to 69 kDa with pH of 5.0-8.2, were found in the nuclei, cytoplasm and extracellular fluid of splenocytes, respectively. One protein, shown in the cytoplasm of splenocytes of control mice, appeared in extracellular fluid of splenocytes after LD-WBI. Two proteins, shown in cytoplasm, and one protein, shown in extracellular fluid of splenocytes in control mice, appeared in the nuclei after LD-WBI. Time-course of protein synthesis varied in different proteins after LD-WBI. These results suggest that alterations of protein expressions and redistribution of proteins between intracellular and extracellular compartments occurred in the splenocytes after LD-WBI. Protein extract from LD-WBI splenocytes was fractionated by Sephadex G-100. Fractions 61-80 contained proteins able to protect lymphocytes in vitro from radiation-induced chromosome aberrations. These findings are of importance in elucidating mechanisms of immuno-enhancement and adaptive response induced by low-dose radiation, although the features and the functions of these proteins remain to be elucidated in future studies.	4 h after 75 mGy X-rays WBI, in the nuclei, cytoplasm, and extracellular fluid of splenocytes, expressions of 20, 15 and 6 proteins, in sizes ranging from 10 to 69 kDa with pH of 5.0-8.2, were changed respectively vs. control mice. One protein in the cytoplasm of splenocytes of control mice appeared in extracellular fluid of splenocytes after WBI. Two proteins in cytoplasm, and one protein in extracellular fluid of splenocytes in control mice, appeared in the nuclei after WBI. Time-course of protein synthesis varied in different proteins after WBI. Protein extract from WBI splenocytes was fractionated. Fractions 61-80 contained proteins able to protect lymphocytes in vitro from radiation-induced chromosome aberrations. This can help elucidate mechanisms of immuno-enhancement and adaptive response induced by LDR, with the protein features and the functions to be elucidated.
55. Chen Dong, Liu Shuzheng, Liu Jiamei. Effect of ionizing radiation on apoptosis in the cortex of mouse lymph node. J. N. Bethune Univ. Med. Sci., 1999, 25(3):223-225.	Abstract Objective: To study the alteration of apoptosis in the cortex of mouse lymph node following whole body X-irradiation. Methods: The method of TdT-mediated dUTP nick end labeling (TUNEL) was used to detect apoptosis the cortex of mouse lymph node. Results: The sensitivity to high and low doses of ionizing radiation was distinct in different area of the cortex. Conclusion: The decrease of apoptotic cells in the internodular and deep cortex indicate that low dose radiation may suppress the apoptosis of T lymphocytes and play a role in immune regulation.	Apoptosis in the cortex of mouse lymph node following X-ray WBI was sensitive to high and low doses distinct in different areas of the cortex. The decrease of apoptotic cells in the internodular and deep cortex indicate that LDR may suppress the apoptosis of T lymphocytes and play a role in immune regulation.
56. Liu Jiamei, Chen Dong, Liu Shuzheng. Effect of ionizing radiation on apoptosis in mouse Peyer’s patches. J. Radiat. Res. Radiat. Proces., 1999, 17(2):93-96.	Abstract The time-effect and dose-effect relationship of apoptosis in mouse Peyer’s patches after whole body irradiation (WBI) with different doses of X-rays was studied by the method of TdT-mediated dUTP nick end labeling (TUNEL). The results showed that the number of TUNEL positive cells in mouse Peyer’s patches were significantly increased following WBI with 2 Gy irradiation while the number of TUNEL positive cells were decreased after WBI with doses of 0.05 Gy and 0.075 Gy X-rays. The results support the view that 2 Gy irradiation promote the apoptosis of immune cells and the low doses of radiation suppresses the apoptosis of immune cells.	Positive cells in mouse Peyer’s patches were significantly increased following 2 Gy X-rays WBI, and decreased after 0.05 Gy and 0.075 Gy. 2 Gy promotes the apoptosis of immune cells, and low doses suppress the apoptosis of immune cells.
57. Ye Fei, Liu Shuzheng. Effects of whole body irradiation with X-rays on cell cycle progression of splenocytes in mice. J. Radiat. Res. Radiat. Proces., 1999, 17(2):111-114.	Abstract The effect of whole body irradiation (WBI) with various doses on cell cycle progression of splenocytes in mice was investigated using flow cytometry. The results showed that DNA synthesis was stimulated within 12~72 h after 75 mGy irradiation, returning to the level of sham-irradiated group on day 7. Meanwhile, after WBI with 2.0 Gy X-rays DNA synthesis was suppressed with significant G₂ block beginning from 8 h, and returned to the level of sham-irradiated group on day 7. The study of dose-effect relationship showed that DNA synthesis was enhanced 24 h after 50 and 75 mGy X-rays, and G₁ block occurred after WBI with 100 and 200 mGy, but DNA synthesis was suppressed with G₂ block and cell division delay 24 h after WBI with 0.5~4.0 Gy.	DNA synthesis was stimulated within 12~72 h after 75 mGy, returning to the sham-irradiated level at 7 d. But after 2.0 Gy X-rays WPI, DNA synthesis was suppressed with significant G₂ block beginning from 8h, returning to the sham-irradiated level at 7 d. DNA synthesis was enhanced 24 h after 50 and 75 mGy X-rays; and G₁ block occurred after 100 and 200 mGy WBI, but DNA synthesis was suppressed with G₂ block and cell division delay 24 h after 0.5~4.0 Gy WBI.
58. Liang Yan, Zhang Ming, Liu Shuzheng. Effects of low dose irradiation on cAMP levels of pineal gland in mice. J.